1. Field of the Invention
Embodiments of the invention generally relate to the field of semiconductor manufacturing processes and devices, more particular, to methods of implanting ions into a substrate by a plasma immersion ion implantation process.
2. Description of the Related Art
Integrated circuits may include more than one million micro-electronic field effect transistors (e.g., complementary metal-oxide-semiconductor (CMOS) field effect transistors) that are formed on a substrate (e.g., semiconductor substrate) and cooperate to perform various functions within the circuit. A CMOS transistor comprises a gate structure disposed between source and drain regions that are formed in the substrate. The gate structure generally comprises a gate electrode and a gate dielectric layer. The gate electrode is disposed over the gate dielectric layer to control a flow of charge carriers in a channel region formed between the drain and source regions beneath the gate dielectric layer.
An ion implantation process is typically utilized to implant, or dope, ions, also called dopants, into the substrate, forming the gate and source drain structure with desired profile and concentration on the substrate. During an ion implantation process, different process gases or gas mixtures may be used to provide ion source species. As the process gases are supplied into the ion implantation processing chamber (such as a P3i™ processing chamber commercially available from Applied Materials, Inc., of Santa Clara, Calif.), a RF power may be generated to produce a plasma to promote ion dissociation in the process gases and accelerate the dissociated ions toward and into the surface of the substrate. The deposited ion profile often results in a peak dopant concentration below the surface. With the advent of smaller features and reduced device sizes, the dopant profile is required to have sufficient concentration of dopants in shallow depths than previously required and reduced concentrations at further depths. Current implantation processes do not produce suitable concentrations of dopants at shallower depths.
Therefore, there is a need for an improved ion implantation process for producing dopant concentrations at depths suitable for semiconductor devices with reduced device sizes.